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13. July 2018

Covestro uses sustainable manufacturing process for chlorine production

Covestro plans to build its own chlorine production plant in Tarragona, Spain. With the so-called oxygen depolarized cathode (ODC) technology, a sustainable manufacturing process is to be used. In Tarragona, the company is building the first industrial-scale plant based solely on this technology. According to the company, Covestro is currently investing around EUR 200 million at Tarragona in order to increase the competitiveness of the location.

According to Covestro, the new plant is a key component for chlorine production, as energy consumption accounts for around one third of chlorine production costs. Chlorine is used in the production of around two-thirds of all polymers. It does not occur in nature, but is always bound, e.g. in rock salt. Electrolysis can produce chlorine from it, but this process is energy-intensive. Covestro and Thyssenkrupp Uhde Chlorine Engineers have developed a technology that reduces energy consumption by around 25 % compared with the usual process, using ODC technology. This is based on the conventional membrane process, which produces chlorine, caustic soda and hydrogen from rock salt and water. The usual hydrogen-generating electrode is replaced by an ODC, which only forms chlorine and caustic soda. This means that the required electrical voltage is only about two instead of three volts.

Two Covestro employees inspect a demonstration plant during a planned downtime in Leverkusen, Germany. (Source: Covestro)

Two Covestro employees inspect a demonstration plant during a planned downtime in Leverkusen, Germany. (Source: Covestro)

“The change in this process sounds simple, but was a ground-breaking development for chlorine manufacturing,” says Hanno Brümmer, Head of Production at the Polyurethanes segment. "Initial invention and development work began in our lab back in 1992. We then developed it further together with Thyssenkrupp and were able to start up the first demonstration plant on an industrial scale in Krefeld-Uerdingen in 2011."

Construction of the new plant in Tarragona is scheduled to begin in the first half of 2019. Chlorine is needed at Tarragona for the production of MDI, a precursor for rigid foams used in buildings and refrigerators to reduce their power consumption. According to Covestro, it cuts CO2 emissions by around 22,000 metric tons per year. This roughly the amount produced by 15,000 cars a year.


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